1. Field of the Invention
The present invention concerns an apparatus for coating one or both sides of a moving fiber web, in particular a paper web or a carton (i.e., cardboard) web, with a liquid or pastous coating material, the apparatus including a coating station for applying a coating onto the web and a non-contact turning apparatus following, viewed in the web's moving direction, the coating station.
2. Description of the Related Art
From WO 98/32921 an apparatus for coating a paper web on one side which includes a coating station and a non-contact turning station is known. After the coating station, in which a coating material is applied onto the moving paper web with the moving paper web being supported by a backing roll, the paper web moves on to a turning roll. From there it travels to a non-contact turning and driving apparatus and moves therethrough. After leaving the non-contact turning and driving apparatus, it is then led to calender-like cylinders which contact and thereby dry the paper web completely. The paper web is then moved on to further processing. In WO 98/32921, for example, an arrangement of four such coating apparatuses in successive sequence is shown, wherein, onto each side of the paper web, a coating material is applied twice. One disadvantage of this prior art coating apparatus is, on the one hand, that the coating is negatively influenced by turning the humid paper web before it has at least partially dried. This disadvantage tends to be even more pronounced since, due to the construction space available, turning rolls with small roll diameters are usually used which leads to a sharp bending of the paper web at the turning point.
In addition, the use of such a turning roll makes it impossible to convert a coating apparatus to an apparatus with which double-coating can be realized since, in this case, the turning roll would be in direct contact with the humid coating which would intolerably influence the coating's quality.
The combination of a non-contact turning apparatus and a non-contact air dryer shown in WO 93/32921, in connection with the non-contact turning and drying apparatus, is, for example, already known from DE 295 11 089 U1. From EP 0 770 731 A1, it is further known to locate a turning apparatus and a drying apparatus under one common housing in order to prevent humid exhaust gas and/or humid exhaust air from escaping into the machine hall.
What is needed in the art therefore is a coating apparatus which at least reduces, if not even eliminates, the risk of quality losses of the coated web.